This invention relates to automated packaging of substrates, particularly (but not exclusively) food-related. Preferred embodiments relate to the automated conveying, selecting, and packaging of food, particularly under aseptic or near-aseptic conditions.
Currently the food industry in particular makes much use of manual labour for packaging. The performance of such packaging systems is notoriously variable, due in part, it is believed, to many of the manual operations associated with packaging being highly repetitive. This is especially the case with the packaging of meat and meat products, where the packers work for comparatively long periods in chilled and damp conditions. Such work can often involve moving heavy items, as well as items that are difficult to handle under the conditions. It is perhaps not surprising that injury to personnel is common, and absenteeism frequent. These factors combine to produce high turnover of staff, and a high and recurring cost of training replacement staff.
Excessive manual handling of food at any stage in its manufacture, including the packaging stage, results in a significant increase in both the type and the number of microbial contaminants. This effect can be compounded by the modern trend towards centralised packing of food, which, although it offers considerable financial benefit, greatly increases the potential for cross-contamination and recontamination. Microbial contamination leads to reduced shelf-life, deterioration in product quality, appreciable waste of material, and overall a considerable loss in value. At least as important as this loss in value, microbial contamination is a major source of human food-borne illnesses.
Automation has the potential to reduce costs, by increasing throughput and reducing or virtually eliminating the requirement for training of staff. Well-designed automated lines can help reduce the incidence and extent of microbial contamination of food: however, the risk of cross-contamination may actually be enhanced because a greater proportion of the throughput is exposed to the same contact surfaces, and if a pathogenic strain is present, the number of consumers becoming ill could increase dramatically.
The packaging industry has already developed a considerable amount of high speed equipment capable of handling, packing and collating very small, regularly shaped items presented in perfect orientation, particularly confectionery. To date, automation of food packaging lines has been limited to packaging small, regularly shaped, fully processed foods; in the meat industry, for example, products such as burgers, pies, and sausages are packaged in a semi-automatic manner in a few factories. Many established methods rely on xe2x80x9cpick and placexe2x80x9d procedures which are inherently slow, and the use of robotics in such methods adds considerably to the cost.
A packaging line embodying the present invention may be able to handle substrates such as foods of a wide variety of different shapes and sizes, at high throughput speeds, and is particularly well-suited to running under aseptic or near-aseptic conditions.
In a first aspect, the present invention provides a method of packaging a substrate comprising (i) conveying the substrate on a conveyor into the field of view of an image analysis system and obtaining an image of the substrate on the conveyor from said system, (ii) comparing the image of the substrate against standard images held in a database, and thereby identifying the substrate and optionally its orientation,(iii) optionally analysing the image of the identified substrate on the conveyor to determine the location of the substrate transverse to the conveying direction, (iv) optionally analysing the substrate image to determine the alignment of the substrate relative to the conveying direction, (v) analysing the substrate image and, with reference to the database if necessary, determining the footprint dimensions of the substrate, (vi) optionally, using the data obtained in any of steps ii-v to effect positional adjustment of the substrate on the conveyor, (vii) selecting a package or a first package component according to the footprint dimensions,(viii) transferring the substrate to the package or component, (ix) providing further components of the package if necessary, and integrating said further components with the first component, and (x) sealing the package. Preferably, the method is conducted substantially within a cavity (eg a chamber or tunnel), said cavity being provided with a plurality of UV sources distributed around the walls of the cavity and directed radially inwardly such that UV radiation from the UV sources maintains substantially aseptic conditions within the cavity throughout the process. The method may form part of a process of handling edible substrates wherein one of the upstream operations includes reducing microbial numbers on the surface of said edible substrate by exposing said edible substrate to UV-irradiation, preferably said upstream operation being effected according to WO94/24875 (or U.S. Pat. No. 5,597,597), incorporated herein by reference.
The image analysis system serves to detect the presence of a substrate in its field of view and may, indeed, serve to locate its position more precisely within that field of view. This detection may be used to synchronise the operation of one or more processes effected downstream.
The conveyor is preferably an indexing conveyor. The conveyor preferably has means defining compartments for confining substrates. Preferably the compartments are defined by barriers to movement (relative to the conveyor) in the conveying direction, whereas at least some displacement in the transverse direction is possible.
I may provide a conveyor having a conveying direction, and means for displacing subjects on the conveyor transversely to the conveying direction. The displacing means may comprise a pusher and means for displacing the pusher over the conveyor, close to it but generally not in contact with it. Thus the pusher may be carried by an endless belt or chain which extends over the conveyor and is preferably drivable selectively in either direction.
I may provide a packaging station adapted to produce a package including a bottom component and one or more liner components (e.g. an absorbent pad and/or a support sheet having support protrusions such as corrugations or raised dimples). The bottom component may have a pair of end portions which are bent upwardly to provide end walls, which may support an overwrapping film out of available to be selected, for whatever reason, the substrate is rejected.
The selection of a component or package may be used to effect sorting and/or grading of the substrate. xe2x80x9cSortingxe2x80x9d as used herein means determining to which category of product a substrate belongs, and selecting a component or package according to a) the footprint dimensions of the substrate image, and b) the category of product to which the substrate belongs; while xe2x80x9cgradingxe2x80x9d as used herein means determining to which class within a category a substrate belongs, and selecting a component or package according to a) the footprint dimensions of the substrate image, and b) the class to which the substrate belongs within a category of product. Accordingly, the method preferably further comprises sorting and/or grading the substrate according to a) weight, or b) product requirements, or c)customer specifications, or d) colour (including discolouration, such as any caused by eg bruising or blood splash), or e) any combination of a-d. Preferably, the method further comprises sorting and/or grading the substrate according to product requirements or customer specifications. Preferably, the method further comprises sorting and/or grading the filled package (ie the package itself and the substrate(s) contained therein) according to product requirements or customer specifications, as an additional contact with a substrate within the package. Note: unless the context requires otherwise, xe2x80x9cfootprintxe2x80x9d and related terms are used herein to refer to the outline of a substrate as viewed in plan when it is in its intended orientation for packaging. It does not generally refer to the area in contact with the support surface, if this is different.
At least part of the method may be conducted in filtered air or in a modified atmosphere; a modified atmosphere being one in which the proportion of at least one of the gaseous constituents is different from the proportion of the said one gaseous constituent in air. Preferably, the modified atmosphere includes inert gas at a higher concentration (in terms of its proportion of the modified atmosphere) than its natural concentration in air. Preferably, the modified atmosphere has the same or a substantially similar composition to a gas mixture which is used in gas packing of the final package.
In many circumstances, the method will further comprise obtaining the weight of the substrate, and preferably including said weight as a factor in selecting the package or first package component step vii. The selection of a component or a package may comprise selecting a conveying line which is provided with the component or package and moving the substrate to said conveying line. If a suitable component or package is not step performed before or after sealing the package.
In a second aspect the invention provides a packaging line which comprises: conveying means; an image analysis system (xe2x80x9cIASxe2x80x9d) suitable for obtaining images of substrates while they are being conveyed on the conveying means; means for comparing said images against standard images held in a database and on the basis of this comparison i) recognising each substrate, ii) estimating the footprint of each substrate, and optionally iii) determining the orientation of said substrate; a placement module; a controller or co-ordinater, able to direct the action of a placement module to select a first package component or a package on the basis of said footprint and arrange for said component or package to receive the substrate on transfer to the placement module; and a final package assembler. Preferably, the packaging line is contained substantially within a cavity (eg a chamber or tunnel), said cavity being provided with a plurality of UV sources distributed around the walls of the cavity and directed radially inwardly. Preferably, the image analysis system is further capable of determining the location of a substrate transverse to the conveying direction. Preferably, the image analysis system is capable of determining the alignment of the substrate relative to the conveying direction. Preferably, the packaging line constitutes part of a processing line in which one of the upstream units or modules is a UV sterilisation unit, most preferably said UV sterilisation unit being as described in WO94/24875, incorporated herein by reference. Preferably, the final package assembler is provided with means for dispensing a modified atmosphere during at least part of the assembly of the final package before sealing the final package.
Preferably, the conveying means comprises one or a plurality of indexing conveyors. Preferably, the conveying means is compartment.
The packaging line may be equipped with reject mechanisms. These may be triggered by the IAS if it does not recognise the object or recognises the object but it is outside a pre-set quality or dimensional criterion.
The packaging line may also be provided with means for positional adjustment, as herein defined, of a recognised substrate. Positional adjustment is preferably under the control of the IAS, either directly, or indirectly via a separate microprocessor controller or programmable logic controller (PLC) (xe2x80x9ccontrollerxe2x80x9d is used herein to encompass either direct or indirect control of the action of downstream equipment by the IAS). Preferably, the means for positional adjustment comprise a plurality of retractable arms provided with blades, said blades being arranged such that the lowermost surface of each blade is close to, but does not touch, the upper run of the conveyor. Positional adjusters are preferably sited on either side of the conveyor so as to be able to act co-operatively in effecting positional adjustment. Preferably, the means for positional adjustment comprises a continuous chain, one or a plurality of pulleys, and a pulley drive, said continuous chain being provided with flanges which in use descend from lower surface of the continuous chain to approach but not touch the upper surface of a product line conveyor. Robotic arms may alternatively be used as positional adjusters. Substrate alignment may alternatively be adjusted by use of variable speed multi-section conveyors. The means for positional adjustment may alternatively or additionally be used as reject mechanisms.
In a preferred embodiment for packaging poultry drumsticks according to the present invention, the conveying means comprises a chute and a primary conveyor, said chute comprising a conically shaped entry head leading to a tubular section with walls which gradually taper to a chute exit. The IAS is positioned so as to obtain an image of a poultry drumstick while the drumstick is on the primary conveyor. The conveying means may further comprise a weigh scale conveyor situated upstream of the chute. In a particularly preferred embodiment, the conveying means comprises a) a processing rail, for conveying drumsticks on gambrels; leading to b) a chute, as just described, for receiving drumsticks following dismounting of said drumsticks from said gambrels; leading to c) a primary conveyor. Preferably, the processing rail is provided with a means for weighing gambrels, with or without drumsticks; a suitable means for weighing gambrels is an in-line weigh beam. Preferably, the image analysis system is further suitable for obtaining an image of a drumstick while it is on a gambrel on the processing rail, in which case suitable means for analysing said image of a drumstick will also be included in the line.
The term xe2x80x9clocationxe2x80x9d is used herein to refer to where a substrate is to be found on a conveyor transverse to the conveying direction; xe2x80x9calignmentxe2x80x9d refers to the agreement between a notional axis of a substrate and the conveying direction; xe2x80x9corientationxe2x80x9d refers to which surface of the substrate is in contact with the uppermost surface of a conveyor (in other words, xe2x80x9corientationxe2x80x9d indicates whether the substrate is the right way up or, for example, upside down); xe2x80x9cpositionxe2x80x9d can encompass one or more of location, alignment, and orientation; xe2x80x9cpositional adjustmentxe2x80x9d means altering the position of a substrate on the conveyor to a different position on the conveyor, said different position being a position suitable for the transfer of the substrate to a base component of a package; a position referred to as being xe2x80x9ccorrectxe2x80x9d is one in which the corresponding substrate is suitably positioned for transfer to a base component of a package, and conversely a position referred to as being xe2x80x9cincorrectxe2x80x9d is one in which the corresponding substrate requires positional adjustment before such a transfer.
The term xe2x80x9cimage comparisonxe2x80x9d is to be interpreted in a broad sense; for example, it is to be understood as including all techniques used in image analysis. As an illustrative and non-exclusive example, it is to be interpreted as including a comparison of two or more data files, at least one of which said files contains connectivity data from or of part or all of a specific edible substrate (the xe2x80x9ctestxe2x80x9d substrate) and at least one other of which said files contains corresponding connectivity data from or of part or all of a further specific edible substrate obtained previously (the xe2x80x9cstandardxe2x80x9d substrate); in other words, every xe2x80x9cimagexe2x80x9d which is to be included in the comparison is described by the image analysis system and/or the reference database mathematically, eg length, roundness, perimeter, major/minor axis, etc. Similarly, the term xe2x80x9cimagexe2x80x9d should be considered, in context, as including the meaning xe2x80x9cimage descriptionxe2x80x9d, ie the image is or has been obtained or stored as a data array in a data file. Some embodiments of the invention will now be described with reference to the figures.